[PSUBS-MAILIST] New Generation Inertial Sensors - Twice as Accurate

Fri Mar 24 21:41:06 EDT 2017

Alan,

That's quite interesting.  I haven't been familiar with acoustic  modems.  
In addition to positioning, I can appreciate that they would have  greater 
range capabilities for communication than the other (but much cheaper)  
technology that we have accessible as amateurs

I've had to pull way back from my focus on sub design and technology for a  
good while.  By the time I return I'm hoping you guys will be field testing 
 Inertial Navigation Systems and have a couple of  different configurations 
to share info on.

Cheers,
Jim 

In a message dated 3/24/2017 3:48:40 P.M. Central Daylight Time,  
personal_submersibles at psubs.org writes:

Jim,
just had a look in Sea Technology magazine March  edition, ( free online 
magazine)
& saw this...
http://www.link-quest.com/html/intro2.htm
It is a small module that tracks an underwater  vehicle, has GPS & 
communicates
to the vehicle via an onboard PC or whatever.  Haven't studied it, but I am 
sure
it could translate the underwater vehicles position  to maps on the 
vehicles PC.
These days you have GPS mapping apps on your cel  phone, so it wouldn't be 
too
hard. The next stage would be using the position  signal from the submarine 
to
control motors on the buoy to follow it. On quad  copters they have GPS & 
return
to start functions that return the quad copter to  it's launch position 
should it's
transmitter lose contact. So the sought of  technology to control the buoy 
thrusters
through position signals is alive & well &  cheap.
   I won't be pursuing it, as I need to  make my sub first :)
Alan

Sent from my iPad

On 25/03/2017, at 6:53 AM, Alan via Personal_Submersibles 
<personal_submersibles at psubs.org>  wrote:

Jim,
yes. Just an intermittent signal every 10 seconds or so. I have
read about text type communication systems.
Here is a passage from a paper that talks about a buoy device.

An  underwater GPS is primarily a combination of a GPS and an acoustic  
positioning system and consists of two types [12-19]: a sea surface buoy  
system using a long baseline and carrying a GPS receiver, which can track,  
monitor, and dynamically position underwater targets from a sea surface,  coastal 
land, and a plane and has a large operating range but can only  position 
underwater targets that carry acoustic transponders in certain  waters; and a 
system which uses a mother ship equipped with a short baseline  or ultra 
short baseline transceiver and a GPS receiver, which is mobile and  flexible 
but also can only position targets equipped with acoustic  transponders. 
Therefore, this paper proposes a way of positioning combining  an ultra short 
baseline, a forward-looking sonar and a GPS receiver,  overcoming the 
limitation of the existing underwater GPS positioning  technology that it can only 
position targets equipped with acoustic  transponders and realizing the 
real-time positioning of the longitude and  latitude coordinates of any unknown 
targets in any waters in the WGS84  ellipsoidal coordinate system, and it is 
also highly mobile. 
Alan 

Sent from my iPad

On 25/03/2017, at 6:06 AM, via Personal_Submersibles 
<personal_submersibles at psubs.org>  wrote:

Alan,
Transmit GPS positions wirelessly where?  You  didn't mean down to the sub, 
did you?
Jim

In a message dated 3/23/2017 10:07:37 P.M. Central Daylight Time, 
personal_submersibles at psubs.org  writes:

Jim,
re the tow behind buoy (pronounced boy); it  would be possible to make a 
buoy with motors on it that tracked your sub  & transmitted GPS positions
wirelessly. Minn kota have a system that  controls their thruster to keep
a boat steady on a certain  coordinate. 
Alan

Sent from my iPad

On 24/03/2017, at 3:43 PM, via Personal_Submersibles 
<personal_submersibles at psubs.org>  wrote:

Here's a link that gives quite a bit of information  including a reference 
to their Windows-based software.  Once you  open the link, the more you 
scroll down the more you will see; it goes  a long way! 
http://www.seismic.com.au/assets/pdf/SBG_Systems-Ellipse_Series_Brochure.pdf

GPS is great as a starting point before you submerge  and for telling you 
where you are once you surface.  Too bad  radio signals don't propagate so 
well under water.  In the  past we've discussed mounting a GPS antenna on a 
Diver Below buoy with  a cable running to the sub.  I don't recall what was 
said  regarding theoretical depth limitations for such a setup as well as  the 
hydrodynamics of towing it.

It would be really interesting to see how well your  INS position matches 
up with your GPS when you resurface.  I like  the idea of knowing just where 
you are with reasonable precision when  submerged, being able to return to a 
precise location on another day,  being able to search or survey 
methodically, navigating from A to B to  C, etc.

Jim T.

In a message dated 3/23/2017 7:55:50 P.M. Central Daylight Time,  
personal_submersibles at psubs.org  writes:

On 3/23/2017 6:40 PM, Brian Cox via  Personal_Submersibles wrote:

There needs to be an underwater GPS   !!

I remember a discussion, long ago,  about a GPS antenna on a mast.  I don't 
recall any  resolution.

Mike

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